Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

physica status solidi (b)

Spectral density method applied to the study of the energy spectrum of the XY model in a transverse field

L. A. B. Bernardes, O. N. Borges, L. A. Amarante Ribeiro

Published Jun 1, 1986• 1 citation
Publisher

Abstract

Abstract The energy spectrum of the XY model in a transverse field is studied by the spectral density method (SDM), using polar and Gaussian „ansätze”︁. Expressions for the critical temperature and critical transverse field are obtained. It is shown that, within some approximations, the static properties of this model are not modified by including damping effects in the elementary excitations.

DOI
10.1002/pssb.2221350216

Related papers

The XY Model with Nearest and Next‐Nearest Neighbour Interaction in a Transverse Field

O. N. Borges, L. A. Amarante Ribeiro, L. L. Gonçlalves

Abstract The one‐dimensional XY model in a transverse field with first and second neighbour interactions is discussed, in the framework of the spectral density method, and in a first order approximation. The ground state is studied in detail and the phase transitions induced by the transverse field are determined. The phase diagram is obtained and it is shown that it presents a bicritical point.

physica status solidi (b)•Oct 1, 1984•0 citations

Spectral density method for the damping of boson elementary excitations in one-dimensional spin S chain

L. S. Campana, M. D’Ambrosio, Ugo Esposito

Damping effects of boson elementary excitations in the Dyson-Maleev representation of one-dimensional spin S chain using the spectral density method (SDM) are studied. For the spectral density the authors use the 'gaussian ansatz', and the reasonable results, obtained in the low-temperature limit, confirm that it is able to describe damping effects in the SDM.

Journal of Physics C Solid State Physics•Nov 30, 1985•2 citations

On the zero temperature critical behaviour of the xy model in a transverse field

J Goldhirsch

A previously developed bosonisation scheme is applied to the investigation of the zero-temperature critical behaviour of the XY model in a transverse field. It is shown how this method yields, in a simple and straightforward way, the results previously obtained using cumulants. The meaning of these results is briefly analysed.

Journal of Physics C Solid State Physics•Dec 28, 1979•11 citations

Density of states in 1D S=1/2 anisotropic XY model with random parameters

Oleg Derzhko, Taras Krokhmaiskii

The determination of the spectrum of the Hamiltonian for 1D s= 1/2 anisotropic nonuniform XY model in transverse field reduces to the determination of the eigenvalues of dynamical matrix for 1D nonuniform chain within harmonic approximation taking into account the interactions between nearest and next nearest neighbours. Therefore Dean's method may be used for finding the density of states. The obtained in such a manner result for isotropic XY model in lorentzian random transverse field, for which an exact result is known, is discussed.

Ferroelectrics•Mar 1, 1994•6 citations

Damping of the Transverse and Longitudinal Excitations of the Ising Model in a Transverse Field

Julia Mihailowa Wesselinowa

Abstract The Ising model in a transverse field is treated by means of the Green function technique to calculate the excitation spectrum and the damping of these excitations above and below Tc. The soft mode is overdamped in the disordered phase and near Tc, while it is nearly undamped at low temperatures. The temperature dependence of the transverse and longitudinal damping for zero wave vector is calculated numerically for different values of the transverse field.

physica status solidi (b)•Jan 1, 1984•8 citations

Ising model in a transverse field. II. Spectral functions and damping

Robin B. Stinchcombe

For Pt. I see ibid., vol. 6, no. 15, 2459 (1973). By taking the (1/z) expansion one order beyond that considered in Pt. I, a detailed discussion is provided of the generalized susceptibilities and spectral functions rho alpha beta of the Ising model in a transverse field Gamma . The leading contributions to the damping of the excitations as well as the first-order shift in their energy and in the critical temperature, are obtained. The damping arises from break-up into (i) a spin wave and a spin fluctuation or (ii) a pair of spin waves.

Journal of Physics C Solid State Physics•Aug 6, 1973•49 citations
Abstract The energy spectrum of the XY model in a transverse field is studied by the spectral density method (SDM), using polar and Gaussian „ansätze”︁. Expressions for the critical temperature and critical transverse field are obtained. It is shown that, within some approximations, the static properties of this model are not modified by including damping effects in the elementary excitations.
The determination of the spectrum of the Hamiltonian for 1D s= 1/2 anisotropic nonuniform XY model in transverse field reduces to the determination of the eigenvalues of dynamical matrix for 1D nonuniform chain within harmonic approximation taking into account the interactions between nearest and next nearest neighbours. Therefore Dean's method may be used for finding the density of states. The obtained in such a manner result for isotropic XY model in lorentzian random transverse field, for which an exact result is known, is discussed.
For Pt. I see ibid., vol. 6, no. 15, 2459 (1973). By taking the (1/z) expansion one order beyond that considered in Pt. I, a detailed discussion is provided of the generalized susceptibilities and spectral functions rho alpha beta of the Ising model in a transverse field Gamma . The leading contributions to the damping of the excitations as well as the first-order shift in their energy and in the critical temperature, are obtained. The damping arises from break-up into (i) a spin wave and a spin fluctuation or (ii) a pair of spin waves.